Simple stud type devices as applied to internal combustion engines have certain known advantages. Nevertheless, there remain voids regarding desirable attributes pertaining to the stud fastening devices, their methods of use, as well as solving and/or overcoming the underlining problems or motive(s) that initially prompted their use.
U.S. Pat. No. 5,025,556 to Stafford is one such example that discloses a method for repairing cylinder head bolt holes located in engine blocks. Stafford discloses a method where a problem cylinder head bolt hole or block hole, located in an engine block, is drilled out, followed by a measuring step to precisely determine the new hole diameter, whereby a custom made stud is created in a subsequent step to precisely fit into the newly created block-hole. The method substantially describes a procedure to create fastening hardware in on-demand, or real-time type of scenario. Such a procedure is not only complex and time consuming, but calls for the use of relatively expensive and complex equipment typically left to specially trained, skilled workers to operate (e.g. a lathe, and the like). The use of an adhesive having a cure time of 12 hours is also included in the repair process. Furthermore, Stafford clearly teaches the application and use of a fine thread (e.g. UNF) types directed to stud or fastener to block-hole interfaces. Unfortunately, fine thread types and corresponding interfaces are more susceptible to cross-threading, have a greater tendency to strip, are more time consuming to install, as well as being more prone to corrosion damage when compared to the coarse thread (e.g. UNC) counterpart. The use of fine thread fastening interfaces, particularly with the more susceptible present day engine blocks fabricated from aluminum based alloys, increase the likelihood of fastener-block interface failure.
Present day cylinder head to engine block bolt type fastener repairs, as well as the teaching of aforementioned U.S. Pat. No. 5,025,556 to Stafford, include the installment of multi-interface coupling devices such as threaded sleeves, threaded plugs, threaded inserts, self-tapping threaded inserts, and the like, into the block-hole. Such multi-interface coupling devices prepare the engine block for receiving the corresponding stud or bolt fastener. The installation of such multi-interface coupling devices can be cumbersome due to the absence of ordinary tool interface features, thereby requiring the use of specialty tools. Furthermore, often such multi-interface coupling devices are prone to premature failure. Such premature failures can be attributed a multitude of causes, including: inherent material weakness involving one or more fastening interface sites, thermal cycling fatigue, coupling device dimensional inadequacies, installation errors, and the like. Additionally, multi-interface coupling devices often exhibit diameter expansion when torque is applied, the strain created has the potential to crack engine blocks as well as strip the sleeve's internal threads.
Overall, a need still exists for a cylinder head to engine block fastening device that is reliable, possesses a long service life, and lends itself to uncomplicated, quick installation. Applications for such an improved fastening device or devices would include: new engine fabrication, retrofitting used engines in need of repair, upgrades, or the like.
The purpose of the present invention is to overcome the long felt need associated with the multitude of shortcomings in the present and aforementioned prior art. Additionally, the present invention includes the introduction of additional novel features giving rise to further advancements resulting in an improved fastening device.